1. Field of the Invention
The present invention relates to a method for producing a thermoplastic resin composition, and particularly, to a method for producing a thermoplastic resin composition which is useful as a material for forming a molded article superior in impact resistance and appearance.
2. Description of the Related Art
Molded articles of polypropylene resins are used in a wide variety of applications due to their superior rigidity, heat resistance and surface luster.
It is known that incorporating an elastomer into a polypropylene resin improves the impact resistance.
For example, JP 2000-26697 A discloses a propylene resin composition superior in processability, physical property balance, low-lustrousness and weld appearance, wherein the composition comprises a propylene-ethylene block copolymer, an ethylene-α-olefin copolymer rubber or propylene-α-olefin-diene copolymer rubber having an MFR of from 0.05 to 1.2 g/10 min., talc and a high density polyethylene.
U.S. Pat. No. 6,399,709 discloses a thermoplastic elastomer composition having a uniformly distributed composition ratio of olefin copolymer rubber and olefin polymer resin and being superior in anti-fogging property, the composition being prepared by feeding a rubber and a thermoplastic resin into an extruder through different feed ports and melt-kneading them.
In the thermoplastic resin compositions disclosed in the above-cited references, the elastomer is not always dispersed sufficiently and further improvement in impact resistance and appearance of molded articles has been demanded.